![Mizoroki-Heck Cross-coupling Reactions Catalyzed by Dichloro{bis[1,1',1''-(phosphinetriyl)tripiperidine]}palladium Under Mild Reaction Conditions](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F51444.jpg&w=3840&q=50)
激活在Pt上的亲体反应组件中的激活(111)
Marc-André Laliberté1, Stéphane Lavoie, Bjørk Hammer
1Département de Chimie, Université Laval, Québec, QC, Canada G1K 7P4.
Journal of the American Chemical Society
|April 3, 2008
概括
三乙烯 (TFAP) 在金表面上形成与气结合的二次体和三次体. 这种自我组装行为可能解释了在类似分子的enantioselective化中观察到的有限速率增强.
科学领域:
- 表面科学和催化剂.
- 有机化学 有机化学
背景情况:
- 三乙 (TFAP) 是一种与不对称催化相关的前体.
- 基的酶选择性化对于合成性分子至关重要.
- 辛科纳类化合物是金催化剂上常用的性修饰剂.
研究的目的:
- 为了研究TFAP在Pt(111) 表面上的自组装.
- 为TFAP相互作用提出一个模型,解释观察到的催化结果.
- 了解分子组合在酶选择性化反应中的作用.
主要方法:
- 在室温下对Pt(111) 上的TFAP吸附和组合的实验观察.
- 理论建议将TFAP自组装与催化相互作用联系起来.
- 对同分子组合中的TFAP激活的分析与二聚体复合物的分析.
主要成果:
- 在室温下,TFAP在Pt上形成C=O···H-C结合的二分体和三分体.
- 这些自组装结构被建议模仿催化系统中的相互作用.
- 观察到的自我组装表明类似的TFAP激活在racemic和chiral网站.
结论:
- 在金表面上TFAP的自我组装提供了一个模型,以了解亲性碳基基拉修饰剂相互作用.
- 这种分子组装机制为阿尔法-基在奥里托反应中缺乏显著的速度增强提供了潜在的解释.
- 了解超分子组织是优化反选择性催化过程的关键.
相关概念视频
02:05Prochirality
The concept of prochirality leads to the nomenclature of the individual faces of a molecule and plays a crucial role in the enantioselective reaction. It is a concept where two or more achiral molecules react to produce chiral products. A typical process is the reaction of an achiral ketone to generate a chiral alcohol. Here, the achiral reactant reacts with an achiral reducing agent, sodium borohydride, to generate an equimolar mixture of the chiral enantiomers of the product. For example, an...
01:11ortho–para-Directing Activators: –CH3, –OH, –NH2, –OCH3
All ortho–para directors, excluding halogens, are activating groups. These groups donate electrons to the ring, making the ring carbons electron-rich. Consequently, the reactivity of the aromatic ring towards electrophilic substitution increases. For instance, the nitration of anisole is about 10,000 times faster than the nitration of benzene. The electron-donating effect of the methoxy group in anisole activates the ortho and para positions on the ring and stabilizes the corresponding...
01:26Photochemical Electrocyclic Reactions: Stereochemistry
The absorption of UV–visible light by conjugated systems causes the promotion of an electron from the ground state to the excited state. Consequently, photochemical electrocyclic reactions proceed via the excited-state HOMO rather than the ground-state HOMO. Since the ground- and excited-state HOMOs have different symmetries, the stereochemical outcome of electrocyclic reactions depends on the mode of activation; i.e., thermal or photochemical.
Selection Rules: Photochemical Activation
Selection Rules: Photochemical Activation
02:34Regioselectivity and Stereochemistry of Acid-Catalyzed Hydration
The rate of acid-catalyzed hydration of alkenes depends on the alkene's structure, as the presence of alkyl substituents at the double bond can significantly influence the rate.
01:11Radical Reactivity: Overview
Radicals, the highly reactive species, gain stability by undergoing three different reactions. The first reaction involves a radical-radical coupling, in which a radical combines with another radical, forming a spin‐paired molecule. The second reaction is between a radical and a spin‐paired molecule, generating a new radical and a new spin‐paired molecule. The third reaction is radical decomposition in a unimolecular reaction, forming a new radical and a spin‐paired molecule. These three...
01:16Cycloaddition Reactions: MO Requirements for Thermal Activation
Thermal cycloadditions are reactions where the source of activation energy needed to initiate the reaction is provided in the form of heat. A typical example of a thermally-allowed cycloaddition is the Diels–Alder reaction, which is a [4 + 2] cycloaddition. In contrast, a [2 + 2] cycloaddition is thermally forbidden.